1. Field of the Invention
The invention relates to crane attachments for construction equipment. In particular, the invention is a crane attachment for a front end loader that is easily installed and does not interfere with the normal operation of the front end loader.
2. Description of the Related Art
In the construction industry, labor and capital equipment costs are the primary variables that effect the cost of a particular project. Of course, in order to remain competitive, a construction contractor must minimize the cost of a project while meeting predetermined specifications. To this end, large machinery has been used to more efficiently handle tasks that were originally accomplished by hand, such as digging, lifting, and moving objects. For example, bulldozers (or graders) have been used to push large amounts of earth for grading and other tasks.
A bulldozer is typically a tractor-like machine having a blade mounted on a frame that extends forward of the tractor body of the bulldozer. The blade is used to push dirt or other objects that need to be moved. The blade can be moved up and down slightly relative to the body to compensate for slopes and other irregularities in the ground. However, a bulldozer is limited to pushing dirt or the like along the ground. In order to lift and move large amounts of dirt or the like, other machinery is necessary. Of course, construction machinery is expensive and is often rented by the hour or by the day. Therefore, limiting the amount of machinery used on a particular project, and making constant use of the available machinery is desirable to limit costs.
In view of this, a device known as a "front end loader" has been developed. A front end loader is the most versatile piece of construction machinery and thus has become the most widely used piece of construction machinery. A front end loader is capable of doing much of the work of a bulldozer and much more. A typical backhoe includes a basic 4-wheel tractor, an articulating arm (sometimes referred to as a backhoe) and a loader pivotally mounted to the tractor. The loader includes a pair of extending loader arms pivotally connected to the tractor, and a bucket pivotally mounted on free ends of the loader arms. Hydraulic cylinders, or the like, are mounted on the loader arms and controlled to cause the bucket to be positioned in various desired positions. The bucket can be lifted high over the tractor or placed on the ground. Further, the orientation of the bucket can be controlled to hold dirt or the like or to dump the same.
However, a front end loader does have some limitations. In particular, a conventional front end loader cannot easily lift large relatively fragile objects, such as HVAC (heating, ventilation, and air conditioning) units or the like. Also, a conventional backhoe cannot lift objects higher than the maximum height of the bucket of the loader and when objects are lifted high, the objects are dangerously positioned over the backhoe operator. Therefore, conventional front end loaders are not suitable for lifting large poles, prefabricated walls, HVAC units, septic tanks, other vehicles or equipment, large trees, or the like. Often such objects must be lifted on a construction sight and thus a crane is also necessary. Of course, the need for a crane increases the cost of the construction project.
To avoid the need for a separate crane, it is known to provide crane attachments for various construction machinery to increase the lifting versatility of the machinery. For example, U.S. Pat. No. 2,301,888 issued to Mosher discloses a crane attachment for a bulldozer. The crane attachment disclosed in Mosher is pivotally attached to the frame which supports the bulldozer blade. However, Mosher does not relate to front end loaders and thus the construction disclosed in Mosher does not address the complexities associated with mounting a crane attachment to a front end loader. In fact, the crane attachment disclosed in Mosher is not suitable for use on a front end loader for several reasons. Specifically, the crane attachment disclosed in Mosher has a curved lower portion that must be mounted on a substantially horizontal member, such as the frame of a bulldozer. This type of mounting cannot be accomplished on a front end loader because the hydraulics, muffler pipe, and other elements of a front end loader would interfere with a crane attachment mounted on a horizontal member. Since Mosher is directed to a bulldozer it does not address this problem. As noted above, bulldozers are not as versatile as front end loaders and are not as prevalent at construction sites. Therefore, Mosher falls short of providing a versatile machine for various lifting and moving tasks.
There have been several attempts at adapting a crane attachment for use with a backhoe. For example, U.S. Pat. No. 3,527,362 issued to Allen discloses a crane attachment for a backhoe that attaches to each end of the secondary arms through a complex set of arms and levers. Also, the crane attachment disclosed in Allen requires that the bucket of the backhoe be removed when the crane attachment is mounted on the secondary arms. Removal of the bucket is not easily accomplished in the field and, at best, is very time consuming. Also, because the crane attachment attaches to the secondary arms through a complex structure and must be coupled to the hydraulic system of the backhoe, each crane attachment must be specifically designed for a particular backhoe. Accordingly, the crane attachment disclosed in Allen cannot be readily deployed in the field and does not permit normal operation of the backhoe. Therefore, Allen falls short of providing a versatile machine for moving and lifting tasks.
U.S. Pat. No. 3,812,979 issued to Leihgeber discloses a crane attachment for a front end loader that does not require removal of the bucket. However, the crane attachment disclosed in Leihgeber mounts on the bucket and is fixed to the bucket. Therefore, the crane attachment must be removed to use the bucket. While the crane attachment disclosed in Leihgeber may be easier to deploy than the crane attachment disclosed in Allen, Leihgeber still falls short of providing a versatile machine for moving and lifting tasks because it does not permit normal operation of the front end loaders without removal of the crane attachment.
In summary, attempts have been made to increase the versatility of front end loaders by providing crane attachments. In attempting to adapt a crane attachment, such as that disclosed in Mosher, prior inventors have found it necessary to use complex connections between the crane attachment and the machinery which interfere with normal use of the machinery. Therefore, the prior art crane attachments introduce limitations. In particular, prior art crane attachments for front end loaders do not provide easy switching between use of the crane attachment and use of the front end loader in a conventional manner.